An undated file photo of the elusive Algerian militant Belmokhtar who might have been killed in US air strikes REUTERS

Al-Qaeda affiliates in Libya have claimed that Mokhtar Belmokhtar, the mastermind of a deadly 2013 attack on an Algerian gas plant, was not killed in a US air strike targeting him.

Ansar al-Shariah, an Islamist group linked to the global jihadi network, released the names of people it said died after two F-15 fighter jets bombed what they believed was Belmokhtar's hideout in the eastern Libyan town of Ajdabiya.

The list of seven didn't feature Belmokhtar, also known as Mr. Marlboro due to his past as a cigarette smuggler across the Sahel and Sahara desert.

"While we eulogize these heroes ... we deny the killing of any other personalities besides those whom we have named who are sons of this land [Libya]," the statement said, according to Reuters.

The veteran jihadist's name was also left out from another victim list by umbrella militant group the Shura Council of Ajdabiya and its Surroundings.

Neither group expressly said Belmokhtar was still alive and both statements could not be independently verified.

Earlier, the internationally recognised Libyan government in Tobruk claimed the senior militant had been killed.

The government led by Prime Minister Abdullah Thinni said: "This air strike was launched by the US Air Force and led to the killing of Mokhtar Belmokhtar. These air strikes were discussed with the US Air Force and were carried out by the international community to help Libya in its struggle against terrorism."

US officials said Belmokhtar was targeted but stopped short of saying he was killed, claiming an assessment of the strike was underway.

Believed to be 43-years-old, the former member of al-Qaeda in the Islamic Maghreb (AQIM) member, was already named as dead once before. In 2013 the Chadian government said its troops involved in French-led anti-terrorism operation in neighbouring Mali had taken his scalp.

However, Belmokhtar, whose many nicknames include Belaouer the One-Eyed, later resurfaced in Libya.

He is on the US wanted list for masterminding the In Amenas BP gas plant siege in which 37 people were killed, including six Britons and three Americans.